Q: iMac 2011 - no wifi connection after sleep under Lion

Solved now with new firmware EFI!!!!!! Install now. Apple very GOOD.

EDIT

Don´t work the same issue. why????

OK, had the issue with 10.7.3, and now it seems to have resolved itself.   Weird.   I am sure it will pop up again however.    Did not do anything to fix it either!

  I called Apple Support and tried a bunch of settings changes   ...with no luck.  It was elevated to a higher level and they had me capture some logged files of the failure to reconnect to WiFi after waking from sleep.  That was yesterday.  The Senior support person working with me called back today and said the engineers were working on it and it would probably be fixed in a software update   ...hopefully soon.

You all know that if you wake your computer with the power button, WiFi connection is fine>  At least it is for me.

:^{)

I have had the same issue with my iMac and 10.7.3. I tried using the power button to wake up my iMac and it worked for me.

Good Luck!

What version of the EFI Firmware do you have, I checked and I have 1.7.

Waosijim: calling their support. I do not know how to do. But it is probably the best thing to do and surely do not try anything else that what they ask you.

On my side, I had this problem since Lion upgrade.  I did several things. I think it is a combination of all that. Now it works fine since 3 days.

I did this ( Please wapsijim do not follow this unless Apple ask you too do, a real fix is what is needed )

Step 1

Remove this file

/Macintosh HD/Library/Preferences/SystemConfiguration/com.apple.airport.preferences.plist

Step 2

In System Preferences / network, Location bar on the top

- there was an "automatic" location

- edit location

- created a new location "Home"

- used this new location

- configured the wifi in "home location" to connect to my home network

Step 3

Upgraded to Lion 10.7.3

Step 4

System Preferences > Network > WiFi > Advanced > TCP/IP tab: Configure IPv6 "Link-local only".

Since step 4, and 3 days, it works for me. In my opinion, this is a combination of step 4 and something else, probably step 1 or 2 who makes this work again.

The versión NEW is 1.8

Don't solve the problem.

I've somehow managed to fix the problem with my 2011 iMac waking from sleep and having no connection at all. It was strange because the 10.7.3 update made things worse for me. I was so frustrated I tried everything all at once so I didn't likely find a scientific fix for everyone. I can't say this will work for everyone but it worked for me and things are finally working smoothly.

1. I deleted my Library - Preferences - com.apple.alf.plist

2. Reset SMC by shutting down computer - unplug for 30 seconds (important)

3. Restarted computer

4. Renamed network SSID and password to ensure complete refresh of preferences for iMac

4. Under advanced tab in wifi preferences deleted any old networks that were not currently used and made sure "new" network was the only one available.

5. Under advanced tab in wifi preferences clicked on Require admin authorization to change networks and click ok.

It was quite frustrating to do all this but it seems things are working perfectly now. Once I wake from sleep I am instantly connected to my home network. Since its a 27" iMac I wont need to change my network.

Strange that its the iMac that has this issue, my MacBook pro is running the exact same Lion update and has never had connection issues.

Hope this helps someone out there

Well, I've just had the same problem right now... maybe it is still not fixed ???

not even after all i've done !??

Naaaaaaaaaaahhhhhhh

deleted (replied in the wrong thread)

I am also encountering this problem.  Since it sounds like it is possible that not all iMac users encounter this issue, here are the details of my installation:

2011 21.5" iMac (MC309LL/A) with a clean install (hard disk wipe) of Lion 10.7.3.  The clean install of Lion was performed from a copy of Lion burned on DVD.(iMac orginally shipped with Snow Leopard installed).  Wireless connection is 802.11n 5Ghz to a 3rd gen Airport Extreme.

Questions:

1) Does this issue impact new iMacs purchased direct from Apple with Lion pre-installed?

2) Are there users of Lion who have upgraded from Snow Leopard who do not have this issue?

I have the exact same problem as well. My iMac is a 21.5 from Jan 2011, Snow Leopard was already installed and I barely use this computer, I bought it just for school. I have a 2009 MBP and have never had a problem. This iMac I always have wake up problems, the main problem now is the wifi. I have to manually reconnect it every time it wakes up. Very annoying and frustrating. Before that, which Apple fixed, it had a hard time waking up by moving the mouse or keyboard.

I've tried everything on this thread more than once, and have upgraded to the recent Lion release on my 3 month old 27" iMac.  Nothing worked EXCEPT, incredibly, waking the computer using the power button.

Waking it up using either the BT magic mouse or the BT keyboard results in a dropped connection.  However, waking it up with the power button results in a reconnect to the WiFi.

!!!!!!!!!!!!!!!!!!!!!!---------------------------------------------------------- ----------!!!!!!!!!!!!!!!!!!!!!!!

APPLE ENGINEERS - I'm sure you are lurking on this thread.  Is it possible that waking the computer via a bluetooth device is at least one of the problems?

Hey Krizbleen, I have a USB keyboard and mouse and have the SAME ISSUE when waking up. It takes my Mid 2011 iMac about 10-15 minutes to finally keep a connection. It will go out about 2-3 times throughout the day after that initial "grogginess" of waking up.

I have not tried to wake up my display (*note! My iMac never goes to sleep because of this issue, I just put the display to sleep*) using the power button, but will try and keep you all posted it that works.

I have the new Lion (i think 10.7.3) update w/ the Airport update installed. It made the issue better, but still have the morning lag and then again it will drop connection a couple times a day.